watchdog: ziirave_wdt: check record length in ziirave_firm_verify()

The "rec->len" value comes from the firmware. We generally do
trust firmware, but it's always better to double check. If
the length value is too large it would lead to memory corruption
when we set "data[i] = ret;"

Fixes: 217209db0204 ("watchdog: ziirave_wdt: Add support to upload the firmware.")
Signed-off-by: Dan Carpenter <[e-mail]>
Reviewed-by: Guenter Roeck <[e-mail]>
Link: https://lore.kernel.org/r/3b58b[e-mail]
Signed-off-by: Guenter Roeck <[e-mail]>
Signed-off-by: Wim Van Sebroeck <[e-mail]>

drivers/watchdog/ziirave_wdt.c

···
 		const u16 len = be16_to_cpu(rec->len);
 		const u32 addr = be32_to_cpu(rec->addr);
 
+		if (len > sizeof(data))
+			return -EINVAL;
+
 		if (ziirave_firm_addr_readonly(addr))
 			continue;